Seiren

Seiren (セイレーン) is a 2 generation, Underwater Warfare Angeloid type η (Eta) (水中戦闘用エンジェロイドタイプη（イータ)) built by the Master of Synapse.

Appearance
She strongly resembles the mermaids of legend with her fin. Seiren's hands also resemble fins. Her wings are floating around her.

Plot
Seiren was impaled in the back by one of Chaos's wings before being devoured, and absorbed by her just after she was ordered by the Master of Synapse to kill Tomoki Sakurai and Ikaros.

Killed by Chaos, who stole her power.

Master of Synapse

 * The Man of Synapse is her master, as well as her creator.
 * Tomoki Sakurai-enemy
 * Ikaros-enemy
 * Chaos-enemy

Trivia

 * Seiren appearance is based on the Seiren of Greek mythology.
 * Even though an Angeloid's weakness is water, Seiren is able to work underwater.
 * Seiren can be in the deepest parts of the water up to 8000 meters deep.